A Manhattan murder jury heard day-long closing statements today in the lurid case of a handsome young Portuguese underwear model who bludgeoned, then castrated alive, his sugar daddy in their Times Square hotel room last year.

Slender, ivory-skinned Renato Seabra was just 21 years old when he admittedly turned on Carlos Castro — an influential fashion writer, also from Portugal, who at 65 was three times his killer’s age.

“He ripped open Carlos Castro’s scrotal sac with a corkscrew, and held the testicles dripping in blood in his bare hands; picture that,” defense lawyer David Touger told the jury, in asking for a verdict of not guilty by reason of insanity.

“When Renato looks down at his hands and saw those testicles, he was in the throes of a mental breakdown and he thought he had just completed the first of his godly-inspired tasks,”

The pair had been vacationing at the posh Continental Hotel. Castro’s body was found on the blood-soaked carpeting of their small, single-bed room. He’d been choked, struck in the head with a computer monitor and gouged in the face with the same corkscrew used to mutilate his genitals.

The defense lawyer described the slaughter today in brutal detail — picking up the shattered monitor and waving it jurors, brandishing the cork screw at them, and finally, stomping his feet on the courtroom floor.

According to medical testimony, Seabra had pounded his sneakered feet into his lover’s head with enough force to leave footprints on the face.

Seabra had no history of violence or mental illness, yet convinced what the defense lawyer described as “an army” of shrinks and social workers that he was bipolar, and had suffered a sudden-onset manic episode.

But prosecutor Maxine Rosenthal argued later today that there was ample evidence that Seabra attacked and then mutilated his dying, still-breathing lover out of fury and revenge.

Seabra had been enjoying Castro’s pricey gifts and modeling connections, and was enraged when Castro broke the relationship off, the prosecutor told jurors.

“The motive is as clear as if it were written in lights on a Times Square marquee,” she told jurors.

And if Seabra was so delusional during the murder, why did he disable the hotel room phone, draw shut the curtains, steal Castro’s cash and put a “Do Not Disturb” sign on the door before leaving, she asked.